Erasure of configurational memory in crosslinked cotton

ABSTRACT

THIS INVENTION RELATES TO A CHEMICAL PROCESS BY WHICH CONDITIONED AND WET CREASE RECOVERY CAN BE IMPARTED TO COTTON FABRICS AND BY WHICH THE CONDITIONED RECOVERY ALONE CAN BE REMOVED WITHOUT DESTROYING THE CHEMICAL CROSSLINKS FORMED DURING THE REACTION BE REACTING THE FABRIC WITH BUTADIENEDIEPOXIDE, MERCERIZING THE FABRIC AND THEN EITHER REACTING THE FABRIC AGAIN WITH BUTADIENEDIEPOXIDE OR HEATING THE FABRIC UNDER VACUUM FOR AN EXTENDED PERIOD.

United States Patent 3,567,362 ERASURE 0F CONFIGURATIONALMEMORY IN CROSSLINKED COTTON Hilda Z. Jung, John B. McKelvey, and Ruth R. Benerito,

New Orleans, and Ralph J. Berni, Metairie, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Nov. 7, 1969, Ser. No. 874,952 Int. Cl. D06m 13/00 US. Cl. 8-120 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a chemical process by which conditioned and wet crease recovery can be imparted to cotton fabrics and by which the conditioned recovery alone can be removed without destroying the chemical crosslinks formed during the reaction by reacting the fabric with butadienediepoxide, mercerizing the fabric and then either reacting the fabric again with butadienediepoxide or heating the fabric under vacuum for an extended period.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

Introduction of reversible crosslinks into the cellulose molecule has been the aim of much research on cotton; that is, a commercially feasible method by which crosslinks introduced into the cellulose molecule might be broken and reformed by suitable chemical techniques. In all of these methods, the crosslinking agent is converted by oxidation-reduction reactions to two separate fragments which may be recombined at will by the reverse of the chemical breaking process.

In contrast, the present invention provides a method whereby conditioned and wet crease recovery can be imparted to fabric and where theconditioned recovery alone can be removed without destroying the chemical crosslinks. After the crosslink has been introduced into the cellulosic fabric with the formation of ether linkages, subsequent conditions of this process preclude any breaking of chemical bonds. However, said conditioned crease recovery can be reintroduced by retreating the cellulosic fabric is treated with butadienediepoxide (BBQ) in the under vacuum.

In the preferred process of this invention, cellulosic fabric is treated with butadienediepoxide (BBQ) in the presence of base catalysis, 2l0% NaOH, to impart high conditioned and high wet crease recovery properties. Crosslinks thus formed are ether linkages and it is well known that such linkages are very stable chemically. The fabric finished with butadienediepoxide still possesses the crystalline structure of native cotton, cellulose I. This fabric is subsequently treated with mercerizing strength caustic, 23% NaOH, which removes the conditioned crease recovery by effecting a change in conformation of the cellulose backbone. X-ray difi'ractograms indicate that postmercerized butadienediepoxide treated fabric possess a crystalline lattice of cellulose IV type. To reintroduce the conditioned crease recovery, the fabric can be retreated with butadienediepoxide or can be heated under vacuum at a temperature of about 160 C. for a period of about 16 hours.

Similar treatment of butadienediepoxide-finished fabrics resulting from cotton cellulose-butadienediepoxide reactions catalyzed by NaOH caused modification of the crystalline structure also. Postmercerization of these cottons containing a mixed cellulose I and II lattice re- Fee sulted in a mixed II and IV lattice. Data are summarized in the following table:

TABLE I [Crystalline structure of BDO-treated altermercerized cotton fabrics] Cellulose lattice-type The following examples illustrate but do not limit the scope of this invention.

EXAMPLE 1 A sample of x 80 printcloth (3.12 oz./yd. weighing approximately 10 gms. was padded twice with 2% aqueous NaOH to approximately wet pick-up and thereafter completely immersed in a 100 ml. graduate cylinder containing 20% by volume of butadienediepoxide (BDO) in carbon tetrachloride solution. The fabric was reacted at room temperature (25 C.) for various times ranging from 5-7 hours. The fabric was removed and the reaction quenched with tap water for a period of ten minutes. After quenching, the fabric was soaked in a mild acid bath for about 5 minutes, then washed free of acid with water, ironed dry, and equilibrated overnight. Weight gains ranged from 5-10%. The conditioned crease recovery angles of the finished fabrics (warp+fill) ranged from 230-250 and wet crease angles from 250270. X-ray diffractograms indicated retention of the cellulose I configuration (that of untreated cotton cellulose). The treated fabric was then immersed in 23% aqueous NaOH for 30 minutes, washed with cold tap water for 1 hour, neutralized with dilute acetic acid for 10 minutes, rinsed again in cold tap water for 15 minutes, and air dried for 16 hours, Postmercerized fabrics exhibited conditioned crease recovery angles of 200 and wet crease angles of 250 270. No weight losses were found on postmercerization showing that the crosslinks were not removed by the treatment. X-ray diffractogra'ms of the postmercerized specimens indicated conversion of crystalline structure from that of native cotton cellulose I to one of cellulose IV type. The fabric had a good hand and exhibited excellent luster after postmercerization.

EXAMPLE 2 Fabric was treated as described in Example 1 except that reaction was for 12-24 hours and weight gains reached 19-27%. Finished fabrics had dry recovery angles of 290-300 and wet crease angles of 280290. X-ray patterns remained that of native cotton-namely, cellulose I. Postmercerization of finished fabrics (as described in Example 1) resulted in a loss of dry crease recovery. Dry crease recovery angles of postmercerized specimens were 205 -211. Wet crease angles of postmercerized specimens were 275 285. X-ray dilfractograms of postmercerized fabrics indicated conversion to a cellulose IV type lattice.

In addition to the above losses in conditioned recoveries and conversion to cellulose IV type lattice, fibers from postmercerized fabrics remained insoluble in cupriethylene-diamine (cuene) and showed no layering when subjected to the layer expansion technique. When stained with Calco Identification Stain II, the original BDO- treated fabrics were rose colored; but postmercerized specimens were green; and ostmercerization caused a reduction in the parallel refractive index onlya char acteristic change occurring when cellulose I is converted to cellulose IV.

EXAMPLE 3 The fabric was treated in all respects the same as in Example 1 except that 6% NaOH catalyst solution was used; and reaction time was 1.5 hours. A weight gain of was achieved. Dry crease angle of the finished fabric was 217, and wet recovery angle was 233. The X-ray diffractograrn indicated retention of the cellulose I crystalline lattice; and finished fibers dyed a rose color when stained with Calco Identification Stain II. Fibers were insoluble in cuene, retaining the shape and convolutions of untreated native cotton cellulose. Indices of refraction remained those of untreated cotton (i.e., cellulose I).

Postmercerization (carried out as in Example I) resulted in modification of the crystalline lattice to a cellulose IV type, and fibers stained green with Calco Identification Stain II. Dry crease angle was reduced to 180 and wet recovery angle was 250. Only the parallel index of refraction was lower than that of native cotton. The perpendicular refractive index remained unchanged and equal to that of native cotton.

EXAMPLE 4 15% NaOH catalyst solution was used instead of 2% in Example 1. Reaction times from 0.6-1.3 hours and addons ranged from 729%. Dry crease angles varied from 231260 and wet recoveries from 300310. X-ray diffractograms showed modification of crystalline configuration to a mixed cellulose I and II lattice. Microscopically fiber sections showed large amount of crosslinking as judged by cuene insolubility; fibers were swollen and had the smooth circular appearance of a well mercerized cotton fiber but showed no layer Separation when layer expansion was applied. Indices of refraction were lower than those of native cotton and equivalent to those of slack mercerized cotton.

Postmercerization of the finished fabric resulted in dry crease angles of 218250 and wet crease angles of 290- 330. X-ray diffractograms showed a change in -crystalline structure to a mixed cellulose IV and II type lattice. Indices of refraction were changed and 1 approached that of cellulose IV. Microscopically, postmercerized specimens showed some swelling, dissolution, and appearance of cracks along the winding of the samples, but there was no separation when the layer expansion technique was applied.

EXAMPLE 5 Fabric was treated as described in Example 1 except that reaction time was 17 hours. A weight gain of 10.7% was achieved. Dry crease angle of the finished fabric was 269 and wet recovery was 276. X-ray dilfractograms showed retention of the cellulose I crystalline lattice. Postmercerization carried out as in Example 1 reduced the dry angle to 217 and had no effect upon wet crease recovery (278). X-ray patterns showed modification of the crystalline lattice to a cellulose IV type structure. Dry

" sequently reintroducing the conditioned recovery alone without destroying the chemical crosslinks which process comprises:

(a) treating the cellulosic fabric with butadienediepoxide under basic conditions,

(b) soaking the fabric from (a) in a mild acid solution,

(c) washing the fabric from (b) free of excess acid,

(d) drying the fabric from (c),

(e) mercerizing the fabric from (d),

(f) washing the fabric from (c) with cold water, then with dilute acetic acid and again with cold water,

(g) drying the fabric from (f), and

(h) retreating the fabric from (g) With butadienediepoxide under basic conditions.

2. A process for imparting conditioned and wet crease recovery to cellulosic fabrics and for removing and subsequently reintroducing the conditioned recovery alone without destroying the chemical crosslinks which process comprises:

(a) treating the cellulosic fabric with butadienediepoxide under basic conditions,

(b) soaking the fabric from (a) in a mild acid solution,

(c) washing the fabric from (b) free of excess acid,

((1) drying the fabric from (c),

(e) mercerizing the fabric from (d),

(f) washing the fabric from (e) with cold water, then with dilute acetic acid and again with cold water,

(g) drying the fabric from (f), and

(h) heating the fabric from (g) under vacuum at a temperature of about C. for a period of about 16 hours. 3. The product produced by the process of claim 1.

References Cited Benerito, Textile Research Journal, vol. 38, pp. 279- 292 (1968).

GEORGE F. LESMES, Primary Examiner J. CANNON, Assistant Examiner U.S. Cl. X.R. 8125 

